Optically active α-fluorocarboxylic acid esters, which are the targets in the present invention, are important intermediates of medicines, agricultural chemicals and optical materials. As typical publicly known techniques relating to the present invention, it is possible to cite Patent Publication 1 and Patent Publication 2. These publicly known techniques are methods in which a reaction-terminated liquid of a dehydroxyfluorination is poured into an inorganic base aqueous solution to fix fluoride ions in the aqueous layer to reduce and remove them.
Furthermore, prior to the present application, the present applicant has found that it is possible to easily produce an optically active α-fluorocarboxylic acid ester, in which fluoride ions have reduced, with high chemical purity and optical purity by reacting an optically active α-hydroxycarboxylic acid ester with sulfuryl fluoride (SO2F2), trifluoromethanesulfonyl fluoride (CF3SO2F) or nonafluorobutanesulfonyl fluoride (C4F9SO2F) in the presence of an organic base and in the absence of a reaction solvent, then adding an acid to a reaction-terminated liquid containing the target product, an optically active α-fluorocarboxylic acid ester, and then conducting a distillation, and an application was already filed [see Japanese Patent Application No. 2007-212495, Example 2 (the first half part), Example 3 (the first half part), Reference Example 1 and Reference Example 2].    Patent Publication 1: Japanese Patent Application Publication 2006-83163    Patent Publication 2: Japanese Patent Application Publication 2006-290870